Prime-mover-control system



c. w. PLACE PRIME MOVEH CONTROL SYSTEM Filed Dec. 29. 1927 Inventor 1 Claude place.

Hi8 Atforngy.

??atented @et. 34, 193 3 uniran STATES rare a r caries CLAUDE W. PLACE, OF LA GRANGE, ILLINOIS, ASSIGNOR T GENERAL ELECTRIC COMEAN'Y, ACOBIPORATIDN OF NEW YORK l PBIME-MQVER-QONTIROL SYSTEM Application filed December 29, 1927. Serial No. 24$,13.

My invention relates to prime mover control systems and particularly to systems for automatically starting prime movers which drive. dynamo-electric machines and one of its objects isto provide an improved arrangement for preventing a prime mover from accelerating to an abnormal speed during the starting operationv thereof.

Another object of my invention is to pro- 19 vide, in a prime mover plant in which the speed of the prime mover isnormally controlled by a motor which operates at a' speed proportional to the speed of the prime mover, an arrangement for controlling the motor so that it will be operative during the starting operation of the plant to prevent the prime mover from accelerating to an abnormal speed.v

In plants where the speed of the prime mover is governed by a motor which operates at a speed proportional to the prime mover speed as is the case where the prime mover drives a generator and the prime mover is controlled by a motor driven fly ball gov- 5 ernor the motor of which is normally energized by the generator, it is important that the motor should be operative to controlthe governor as soon as the prime mover reaches its normal speed during the starting opera- 39 tion so as to prevent the prime mover from runningaw'ay. In accordance with my invention, I provide, an arrangement whereby during the starting operation, the governor motor is controlled"independently of the speed of the prime mover so that it is operative to limit the speed of the prime mover during the starting operation.

My invention will be better understood from the following description taken in con- 0 nection with the accompanying drawing a single figure of which shows diagrammatically a control system for a prime mover dynamo-electric plant embodying my invention,

andits scope will be pointed out in the appended. claims.

Referring to the drawing l represents a prime'm'over dynamo-electric plant comprising a water wheel 2 driving a generator 3 and an exciter 4. The supply of fluid energy to the water wheel 2 may be controlled by any suitable means such as a ate 7 which in turn is controlled bfy any suita le governing means 8 examples 0 WlllChfiZe well known in the art.

means iomprises a motor driven fly ball governor having-a movable member 10 which is arranged in any suitable manner examples of which are well known in the art so that the position thereof determines the opening of the gate. As diagrammatically shown in the drawing the member 10 is in the gate closed position and is held in that position by a closing spring 11 against the bias of an operating spring 12 as long as a ma net 13 is deenergized. .Whenever it is desired to place the prime mover 1 in operation it is necessary to energize the magnet 1.3 which is so arranged that its energization moves the closing spring 11 out of operative relation. with the member 10 and allows the spring 12 to'move the member to ,a gate opening position. As long as the magnet 13 is energized the gate opening position of the member 10 depends upon the position of the fly balls 15, which may be driven at a speed proportional to the speed of prime mover by any suitable means such as an electric motor 16 which is normally arranged to be energized by the generator p The generator 3 is arranged to be connected to a load circuit 18 by suitable switching means 19 and the exciter 4 is arranged to be connected to the generator field winding by suitable switching means 20. The operation of the switching means 19 and 20 may be effected in any suitable manner either automatically or manually, examples of which are well known in the art. As shown in the drawing switching means 19 is manually controlled and the switching means 20 is arranged to be closed by a winding 21, which is responsive to the exciter voltage, when the exciter voltage is above a predetermined value.

The initial energization of magnet 13 to start the plant may be eiiected in any suitable manner examples of which are well known in the art. As shown in the drawing the circuit of the magnet 13, when the plant As shown in the drawing the governing is shut down, is arranged to be completed by a switch 23. In order to effect a decrease in the gate opening as soon as the plant starts I provide a speed switch 24 which is responsive to the speed of the prime mover and which is arranged to effect the opening of the original starting circuit ofthe magnet 13 as soon as the prime mover speed reaches a predetermined subnormal value.

It will be noted that due to the slow rate at which the exciter and generator voltages may build up the motor 16, if it were permanently connected to the generator, probably would not be up to its normal speed so as to limit the gate opening to its proper value, by the time the prime mover would reach its normal speed during the starting thereof. a

In order that the fly balls 15 may be rotating at substantially normal speed and thereby be operative to limit the position of the member 10 toits normal operating position by the time the prime mover has accelerated to its normal speed, I provide an arrangement whereby during the starting operation the motor 16 is first connected to an auxiliary energized source of current 25 and then when the generator is in an operative condition to supply current to the motor it is transferred from the auxiliary source 25 to the generator 3. g

For connecting the motor 16 to the auxil iary source 25 I provide a switch 27 which is arranged to be closed in any suitable manner when the speed of the prime mover is above a predetermined subnormal value. As

shownthe switch 27 is provided with a closing coil 28 the circuit of which is arranged to be completed in response to the closing of the contacts 36 of the speed responsive means 24. I also provide a switching device 29which is arranged to be operated to disconnect the motor '16 from the source 25 and to connect the motor 16 to the generator 3 when the generator is in an operative condition to supply current to the motor 16. Any suitable means, examples of which are well known in the art, which is responsive to a predetermined condition of the generator indicating the operative condition thereof such as the speed, voltage, frequency, etc., may be employed to control the selective operation of the switching means 29. As shown in the drawing the switching means 29 is provided with an operating coil 30 which is arranged to be connected across the generator 3 when the switch 20 is closed and which is designed to operate the switching means 29 so as to connect the motor to the generator 3 only when the generator voltage is above a predetermined value. generator voltage depends upon the escitation and speed of the generator it is evident that the operation of the switching means also depends upon both the excitation and Since the 5 speed of the generator. Preferably the necessary generator voltage to operate the switch 29 can be obtained only when the generator is operating at a higher speed than the speed at which the speed responsive device 24 closes its contacts. In order to reenergize the governor magnet 13 after its circuit has been opened by the operation v33 may be designed in any suitable manner so that it does not operate to rcenergize the magnet 13 until a predetermined time after the voltage impressed on the relay 33 is above a predetermined value. Such an arrangement may be desirable in order to insure a predetermined closing of the gate after the prime mover starts. a

The operation of the system shown in the drawing is as follows:

When it is desired to start the prime mover plant the switch 2-3 is 'closedsothat themagnet 13 is energized through contacts 3 1 on switch 27 to move the" closing spring 11 out of operative relation with the member 10 and to permit the operating spring .12 to move the member 10 to a gate opening position. If desirable, the opening move .ment of the member 10 may be retarded in.

any suitable manner such as a dash pot The governor 8'continues, to open the gate 7v until the waterwheel 2 starts and the speed thereof reaches a value sufllcient to cause speed responsive means 24 to close its contacts .36. A circuit is then completed for the closing coil 28 of switch 27 so that thetiy ball motor 16 is connected across the auxlllflly energized source 25 and the original energizing circuit of the magnet 13 is opened at auxiliary contacts 34. The closing spring 11 then causes the member 10 to 'move towards the gate closing position so that the gate 7 in turn is moved towards its closed position to decrease the supply of water to the water wheel. As-soon as the switch 27 closes, the motor 16 starts to ro+ tate and comes .up t'oits normal speed very quickly. Preferably the frequency of the source 25 is substantially thesame as the normal frequency of the generator 3 so that the fly balls 15 when the motor 16 is connectedto the auxiliary source maintains the speed of the water wheel at siilirstantially v the same value it does during normal operating conditions when it is connected to the generator. I'Vhen the voltage across the terminals of the motor 16 builds up to a pre determined value, relay 33 becomes operanvvonoe ive to close its contacts 38 thereby reenergize the magnet 13. This "feature of controllingthe excitation of the magnet 13 so that a decrease in the gate opening is effooted as soon as the Water wheel speed reaches a predetermined value is claimed in applicents divisional application Serial No. 351,2?4, filed March 30, 1929.

As the water wheel accelerates the voltage of the exciter i builds up and when it reaches a predetermined value switch 20 closes its contacts i and. 41. The closing of th contacts 40 connects the generator field across the terminals of the exciter i and the closing of the contacts ll connects the closing coil 36 of ihe switchinq means 29 across the generator terminals so that when the generator voltage is above a predetermined value the switching means 29-is operated to disconnect the ball motor 16 from the auxiliary source :25 and to connect the motor 16 across the generator terminals. The fly balls are then driven at a speed dependent upon the frequency of the generator S'so that the position of the gate 7 is controlled to maintain the speed of the water-wheel at a predetermined value.

it will he noted that if the exciter fails or any other abnormal condition occurs so that either the winding 21 or the winding 30 hecomes deenergized while the plant is in operation, the switch 29 operates to reconnect the motor 16 to the auxiliary source so as to prevent the prime mover from running away.

While I have in accordance with the Patent Statues shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art, and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scop e of my invention.

. ldfhat I claim as new and desire to securecomprising a device and means for normally said. device to operate at operating said device at a speed dependent upon the speed of said prime mover, means for starting said prime mover, and means for edecting the operation of said device at substantially its normal speed prior to said prime mover reaching its normal speed durmg the starting operation thereof.

2. In combination, a prime mover, a governor for said prime mover, a speed responsive device for controlling theoperation of said governor, means for causing said device to operate at a speed which varies with the speed of said prime mover, means for causing a speed which is independent of the speed of said prime mover,

' and means dependent upon a predetermined condition or said prime mover iorselectively controlling which of said last mentioned means controls the operation of said device.

3. in combination, a prime mover, a generator driven by said prime mover, a fly ball governor for controlling the speed of said prime mover, an electric motor for driving the ily calls of said governor, a source of current, and means dependent upon the voltage of said generator for selectively controlling the connection of said motor to said generator and to said source.

4-. in combination, a primemover, a generalor driven o said prime mover, a fly ball governor for controlling the speed of said prime n1over,an electric motor for driving the fly balls of said governor, a source of current, and means dependent upon the speed of said generator for selectively controlling the con nection of said motor to said generator and to said source.

5. In combination, a prime mover, a genertor driven by said-prime mover, a fly ball governor for conirolling' the speed of said prime mover, an electric motor for driving the fly halls of said governor, a source of current, and means controlled in accordance with the excitation of said generator for selectively controlling the connection of said motor to said generator and to said source.

8. In combination, a prime mover, a genertor driven by said prime mover, a fly ball governor for controlling the speed of said prime mover, an electric motor forx driving the fly balls o'fsaid governor, a source of current, means for connecting said motor to said source, and means responsive to a predetermined condition of said generator for efi'ecting the disconnection of said motor from said source and the connection of said motor to said enerator. '1 'n combination, a. prime mover, a gen orator driven by said prime mover, a. fi ball governor for controlling the speed c said prime mover, an electric motor for driving the fly balls or" said governor, a source of current, switching means for connecting said motor to said source and to said generator, and electro-res ponsive means energized by said generator for selectively controlling said switching means.

8. In combination, a prime mover, a genorator driven by said prime mover, a fly ball governor for controlling the speed of said prime mover, an electric motor for the lily halls of said governor, a source of current, means for connecting said motor to said source, and means responsive to a predetermined condition of said generator indicating that it is in condition to supply current to said motor for effecting the disconnection of said motor from said source and the connection of said motor to said generator.

9. In combination, a prime mover, a genorator driven by said rims mover, a fly ball governor for controllingthe speed of said driving prime mover, an electric motor for driving the fly bellsof said governor, a source of current, means responsive to a predetermined condition of said generator for effecting the connection of said motor to saidisource, and means responsive to another predetermined condition of said generator for effecting the connection of said motor to said generator.

10. In combination, a prime mover, a generator driven by said prime mover, :i fiy ball governor for controlling the speed of said prime mover, an electric motor for driving the fly balls of saidgovernon a, source of current, means responsive to a predetermined subnormal speed of said prime mover for effecting the connection of said motor to said source, and means dependent upon a higher speed of said prime mover for eifecting the discoi'mection of said motor from said source, and the connection of said motor to said generator.

In Witness whereof I have hereunto set my hand this 27th day of December, 1927;

CLAUDE W. PLACE. 

